Rafflesia: The Super Flower

by Edward S. RossMore bizarre than beautiful, the Rafflesia flower I had journeyed halfway around the world to see blazed before me. Its five brilliant red petal-like lobes formed a circle a meter in diameter. In place of the tissue-thin petals of a rose were thick, fragile flaps rather like the flesh of a mushroom in texture. The flowerâs opening was bordered by a thin-walled diaphragm, which was probably concentrating the odor of rotting flesh that had attracted a buzz of filth flies.

Despite the smell, I counted myself lucky. Botanists from around the world make special pilgrimages to the rainforests of southeastern Asia hoping to see these extraordinary blossoms. But, more often than not, their quest fails. The plants are scattered and hard to reach, and their blooming periods are short and unpredictable.

I had long wanted to feast my eyes on a Rafflesia. The opportunity first arose during one of my insect collecting forays in Indonesia. I made a special trip to Batang Palupuh, a small Sumatran village near Bukittingi. There, a roadside sign reading âBunga Rafflesiaâ (Rafflesia flower) announced the flowerâs presence. A short hike to the gated, guarded spot led through a rural village with rusty-metal-roofed houses, a mosque, rice paddies, and aromatic cloves and cinnamon bark spread to dry in the sun. I was rewarded by the smiles of villagersâperhaps offered in sympathy because they knew that the Rafflesia werenât in bloom.

A year later, I returned to Sumatra better prepared. Traveling on an enabling grant from National Geographic, I had the blessings of the leading authority on Rafflesia, Willem Meijer of the University of Kentucky. Meijerâs contact, a local forester, guided me along the densely-forested slope of a volcano to a âsecretâ locality. I promised not to divulge the name so as to avoid attracting well-meaning but potentially habitat-damaging visitors.
This time, I arrived while the flowers were in full bloom and ample stench. It was a rare experience.

Rafflesia flowers are considered the prima donnas of Earthâs floral stage. Dramatically huge, vividly-hued lobes bordered the flowerâs broad circular basin. Numerous depressions marked the upper surface of its diaphragm. I learned that these are produced by the pressure of the lobe warts when the flower is still just a bud. In turn, these depressions appear as elevated, pure-white spots on the lower surface of the diaphragm. Further down, inside the corolla of petals, were reddish, tentacle-like, branched âramentae,â which are thought to be the source of the flowerâs carrion-like odor.

To more thoroughly photograph the flowerâs details, I asked for permission to dissect a specimen. It was one of the numerous male flowers in the area, and its age suggested that its pollen had already been harvested. A broad cylinder rose from the heart of the flower, its flat top covered with erect, spike-like projections. A fold beneath the rim hid a ring of yellow-tipped wartsâthe anthersâwhich exuded slimy pollen. In female flowers, which are much rarer, tiny, peanut-shaped seeds develop by the thousands in the heart of the central column.
For much of the year, Rafflesia seems to be absent from the forest floor. But later, buds and flowers appear to rise from the ground. Closer inspection reveals that the flowers are slowly emerging from lianas buried in forest leaf-litter.

In fact, Rafflesia are leafless parasitic plants residing just beneath the rough bark of lianas in the genus Tetrastigma. They send out nutrient-absorbing threads known as haustoria to penetrate the tissues of host vines. Well-adjusted freeloaders, Rafflesia donât kill their hosts: their haustoria simply sap some of the nutrients produced by the hostâs leaves and, of course, the water and minerals its roots draw from the soil. Unfortunately, foresters frequently cut and destroy lianas to reduce competition in the canopy and increase the growth of timber trees. In so doing, they unwittingly accelerate the extinction of rafflesias. Read more.